Knife-holding means for chipping machines



Dec. 16, 1930. c. B. SPRAGUE A KNIFE HOLDING MEANS FOR CHIPPING MACHINES Filed May 20, 1929 ar/ar I Patented Dec. 16,1930

cHAnLns B. sen-neon, or ronrrnnngonneon KNIFE-HOLDING MEANS: FQB, CHIPPING "MA'oHr Es Application filed May 20,

My invention relates to chipping machines or hogs used in the reducing ofwood fiber or other organic materials tochips and particularly to the cutter head and blade holding a means therefor.

Heretofore the knives of these chipping machines which are subjected to very severe duty have tended in use to loosened in their sockets and have their cutting edges dulled or broken, in the latter instance because pieces of metal and other foreign substances are frequently intermixed with the organic matter being chipped.

Furthermore, the knife blades commonly used are provided with elongate slots in which, the holdingbcltsare inserted. These slots tend to weaken the knife blade and to shorten. its period of usefulness, as the slots are of substantial .lengthand only permit the knife to be resharpened a relatively few times as it can only be ground back a short distance because of the said bolt slots.

Thereforethe object of my invention is to provide simple and practical knife. holding means for the rotary cutter heads of these machines, adapted to clamp the knives firml and rigidly in place without the use of knife holding bolts, requiring elongate slots in the knife blade itself, thereby permitting the use p of a knife blade which is strong and because 1t requires no elongate slots, the knife 1s more economically manufactured and W111 have a longperiod of usefulness since it maybe re- I sharpened as long as sufticient width remains to the knife blade to be held securely by theknife holding means.

A. further object of my invention is to provide knife holding means adapted to permit the knife yield under undue strain, as when a piece of metal is encountered by the knife blade ing dulled or broken and. the holding means from being wracked and loosened by the said undue resistance to the knife blade.

A still further object of my inventionis to provide blade holding means releasable from the exterior of the cutter head permitting the blade to be conveniently removed without dismounting the cutter head.

I attain my objects in a chipping machine become rapidly thus saving the cutting edge from be-,

1929. Serial in. 364,594.

. consisting of hollow cylindrical cutter head provided with lon itudinal knife receiving slots provided with interior plane ffacedkni'fe seats, the interior endof the knife seats pm vided with a transverse slot, a knife-'holdin'g bar provided at its inner end with a retaining rib engaging in said the heel end of said bar to the wall of the cylinder, a knife clamped by. said bar to said seat,knife holding screws threaded in said rib, springs between the points ofsaid screws and the heel of the knife, and'the clamping face of said bar having a taper from its toe rearward for the purpose mentioned.

These and other incidental features of my invention, the detailsof construction and the mode of operation thereof are herein-after fully described with reference to the accompanying drawings: i i

In the drawings j Fig. 1 shows a front View of a chipping machine with the upper half of the housing re moved, disclosing the cutter head and its bla es Fig. 2 shows an enlarged section taken on Fig. 4, shows a view looking from under-' neath the .knife and the holding means as shown inFig. 3; and

ig. 5 shows a perspective view of the blade and knife hol'dingmeans separated one from the other groove, the outer edge ofsaid bar sloping rearward, bolts securing Referring now to thefigures The chipping machine which may be of any standard form, comprises in this embodiment, a housing a, a cutter head 6 journaled therein, ter' head carrying knives c and an anvil knife (Z againstjwhich the said knives c operate as the cutterjhead is rotated. The cutter head 6 is composed of two frustro cones attached at their smallerends and provided with staggered,longitudinal knife recei'i' i'ng slots 6%.

the cutholding bar 1' provided with bolt recesses z" and a transverse rib ad acent its inner end is adapted to be secured on the knife seat 9 with the rib j inserted in the groove h. The knife holding bar 6 is also tapered rearwardly from the cutting edge on the underside as at Bolts Z are provided for securing the said blade holding baron the knife seat, which are inserted through the bolt'recesses z" of the knife holding bar 2' and through bolt recesses b in the cutter head I) with which the bolt recesses a are arranged to register. By this construction. the bolt recesses b are arranged a substantial distance from the slot 0, thus not tending to weaken the knife seat 9 as would be the case were the bolt recesses near the slot 0.

A knife blade 0 is arranged between the knife hold ng bar 71 and the seat 9. Set screws 71. provided with guide stems n on their threaded ends are threaded in the rib j and coil springs 0 are arranged over said stems n to bear against the heel c of the knife 0, so that any undue resistance such as the edge of the knife striking a piece of metal interm xed with the material being chipped will permitthe knife to yield longitudinally against the springs and thus save it from being broken.

The inner face of the knife holding bar 71 is tapered slightly from its toe 11 toward the r b 7', as at 79, so that the knife 0 is held most firmly by the toe of the'bar and the tightening of the bolts Z will tend to spring the bar i so as to bear against the knife 0 for its full length, thus firmly holding the knife and locking the bolts in place.

The sides of the bar i are cut away as at q to permit the edges of the knife 0 to project beyond, whereby projections are formed by which the knife may be conveniently removed from the hold ng means after the bolts Z are loosened, by tapping it out of place.

Lock washers a" are provided on the bolts Z to prevent their nuts from becoming loosened by the vibration of the rotation of the cutter head.

I claim:

1. In a rotary cutter the combination of a hollow cylindrical head provided with longitudinal knife receiving slots, the cylinder wall provided on the interior with a plane face constituting a knife seat, the interior end of said knife seat provided with a groove, a knife holding bar provided at its inner end with a retaining rib engaging in said groove, a knife clamped by said bar to said seat and the clamping face of said bar having a taper from its toe rearward for the purpose mentioned.

2. In a rotary cutter the combination of a hollow cylindrical head provided with longitudinal knife receiving slots, the cylinder wall provided on the interior with a plane face constituting a knife seat, the interior end of said knife seat provided with a groove, a knife holding bar provided at its inner end with a retaining rib engaging in said groove, bolts securing the heel-end of said bar to the wall of the cylinder, a knife clamped by said bar to said seat, knife holding screws threaded in said rib and springs between the points of said screws and the heel'of the knife.

3. In a rotary cutter the combination of a hollow cylindrical head provided with longitudinal knife receiving slots, the cylinder wall provided on the interior with a plane face constituting a knife seat, the interior end of said knife seat provided with a groove, a knife holding bar provided at its inner end with a retaining rib engaging in said groove, bolts securing the heel-end of said bar to the wall of the cylinder, washers on said bolts, a knife clamped by said bar to said seat, knife holding screws threaded in said rib, springs between the points of said screws and the heel of the knife and the clamping face of said bar having a taper from its toe rearward for the purpose mentioned.

In a rotary cutter the combination of a hollow cylindrical head provided with longitudinal knife receiving slots, the cylinder wall provided on the interior with a protrusion at one side of each slot having a plane face constituting a knife seat, the interior end of said knife seat provided with a groove, a knife holding bar provided at its inner end with a retaining rib engaging in said groove, the outer edge of said bar sloping rearward, a knife clamped by said bar to said seat, knife holding screws threaded in said rib and springs between the points of said screws and the heel of the knife.

5. In a rotary cutter the combination of a hollow cylindrical head provided with longitudinal knife receiving slots, the cylinder wall provided on the interior with a protrusion at one side of each slot having a plane face constituting a knife seat, the interior end of said knife seat provided with a groove, a knife holding bar provided at its inner end with a retaining rib engaging in said groove, the outer edge of said bar sloping rearward, a knife clamped by said bar to said scat, knife holding screws threaded in said rib, springs between the points of said screws and the heel of the knife and the clamping face of said bar having a taper from its toe rearward for the purpose mentioned.

CHARLES B. SPRAGUE. 

